Tore Flåtten

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We consider systems of hyperbolic balance laws governing flows of an arbitrary number of components equipped with general equations of state. The components are assumed to be immiscible. We compare two such models; one in which thermal equilibrium is attained trough a relaxation procedure, and a fully relaxed model in which equal temperatures are(More)
Stabilization of casing-heading instability from gas-lift wells is important since it increases production and reduces operational problems. This thesis is a contribution within feedback control stabilization of gas-lift wells with casing-heading dynamics. The main advantage of stabilizing the gas-lift well by feedback control, compared to traditional(More)
The aim of this paper is to construct semi-implicit numerical schemes for a two-phase (two-fluid) flow model, allowing for violation of the CFL criterion for sonic waves while maintaining a high level of accuracy and stability on volume fraction waves. By using an appropriate hybridization of a robust implicit flux and an upwind explicit flux, we obtain a(More)
We consider a hyperbolic system of conservation laws describing multicomponent flows through a transport pipeline, with applications to CO 2 transport and storage. We demonstrate that numerical dissipation easily leads to an underestimation of the amplitude of pressure pulses and the resulting pipe strain. We argue that recently developed high-resolution(More)
We explore the relationship between two common two-phase flow models, usually denoted as the two-fluid and drift-flux models. They differ in their mathematical description of momentum transfer between the phases. In this paper we provide a framework in which these two model formulations are unified. The drift-flux model employs a mixture momentum equation(More)
We consider an isolated system of N immiscible fluids, each following a stiffened-gas equation of state. We consider the problem of calculating equilibrium states from the conserved fluid-mechanical properties, i.e., the partial densities and internal energies. We consider two cases; in each case mechanical equilibrium is assumed, but the fluids may or may(More)
We present a multi-stage centred scheme, of the kind proposed by Toro [Appl. Numer. Math. 56 (2006) 1464], for numerically resolving the simultaneous flow of two fluids through a transport pipeline. This model contains non-conservative terms in both the temporal and spatial derivatives, and an extension of the standard numerical framework for conservation(More)
In this paper we propose a class of linearly implicit numerical schemes for a two-phase flow model, allowing for violation of the CFL-criterion for all waves. we here develop an extension denoted as Strongly Implicit Mixture Flux (SIMF). Whereas the WIMF schemes are restricted by a weak CFL condition which relates time steps to the fluid velocity, the SIMF(More)